Geomorphology

Reef Types

This overview of the main reef formations is not exhaustive. This page presents briefly the notion of seascape and the main classical geomorphological reef-types (atoll, bank, fringing, barrier, patch). There are many variations and other geomorphological sub-classes that we identify and map using images.

One of the challenges of this project is that the global reef classification scheme we are building will be derived from modern, horizontal structures as seen from space. But to be accepted by the scientific community, the typology needs also reflect the geological history of the reefs and be in agreement with decades and centuries of habits, at least since Charles Darwin's work.

Reef geomorphology is not "linear". Reef types do not necessarily fit into the traditional Darwinian fringing-barrier-atoll sequence. The geological history controls the modern geomorphology of many reefs. Pre-Holocene topography provides the foundation where reef-building organisms have flourished and grown in a vertical or horizontal mode according to the variations of sea-levels. Then, within a region, antecedent reef topography, modern reef growth and erosion, tectonic events, eustatic variations, oceanic hydroclimate and rainfall patterns have modulated the geomorphology we can observe now from space.